1. Field of the Invention
The present invention relates generally to a magnetic recording medium, and more particularly a magnetic recording medium having a thin film of ferromagnetic metal formed on a non-magnetic substrate.
2. Description of the Prior Art
Recently, a thin film of ferromagnetic metal has been noted. A magnetic recording medium of this kind is made by such a manner that ferromagnetic metal or alloy is formed on a non-magnetic substrate by liquid-phase plating and the physical vapour deposition technique such as vacuum deposition, sputtering, ion plating or the like. Since this type of the magnetic recording medium includes no non-magnetic binder such as resin or the like in its magnetic layer, the magnetic material is high in packing density and hence even if the magnetic layer is thin, residual magnetic flux density can be increased. Therefore, this type of the magnetic recording medium is suitable for recording a short wave length signal.
Since, however, in this magnetic recording medium, total is exposed on the surface of the magnetic layer thereof, if the magnetic recording medium is, as it is, transported in contact with a magnetic transducer head, drum guide member and so on, due to the fact that the friction of the magnetic recording medium on the part in contact with the above elements is large, the magnetic recording medium is easily damaged. Therefore, such a trial has been carried out in general that a certain lubricant is coated on the surface of the magnetic layer to decrease its friction coefficient. In this case, however, since the magnetic recording medium includes no binder material as previously explained, the lubricant is merely coated on the metal surface of the magnetic layer. Therefore, when the magnetic recording medium is repeatedly transported in contact with the magnetic transducer head, the lubricant is easily peeled off from the metal surface and accordingly, the effect of the lubricant disappears in a short period of time.